This invention relates to the field of differential pressure measurement and more particularly to a measurement mechanism for differential pressure measurement.
Measurement mechanisms for differential pressure measurement are typically based on a differential pressure measurement cell, which is produced in silicon-glass micromechanics and has an elaborate external arrangement for limiting the maximum differential pressure. A technical difficulty in this case involves, in particular, the pressure-tight connection of the measurement cell to the pressure feed. This is typically achieved by means of connecting pieces soldered or anodically bonded onto the silicon. Via this connecting piece, the pressure is fed from outside to the sensor, which is located in a small metal housing. This generally requires a plurality of connection points, which have to be welded or soldered.
The resulting multiplicity of soldered connections leads to a technically demanding fabrication process. Furthermore, soldered connections hinder straightforward repair of the measurement mechanism by replacing the sensor cell in the event of a fault.
The measurement mechanism itself takes care of pressure limitation by means of an oil store and a plurality of diaphragms. It likewise forms the interface with the macroscopic environment, in particular the flanges of a pipeline. The oil store also makes it more difficult to repair the measurement mechanism.
It is therefore object of the invention to provide a measurement mechanism those structure permits straightforward repair by replacing the sensor cell in the event of a fault. The present invention achieves that object.
The invention is based on a measurement mechanism for differential pressure measurement, which essentially consists of two housing portions, an electronics board and a differential pressure sensor.
According to the invention, the housing portions are designed in flange form, and the differential pressure sensor is inserted with a force-fit between the flange faces of the housing portions. The electronics board is connected to the differential pressure sensor via a force-fit electrical contact.
The effect advantageously achieved by this is that, after the housing has been opened and the force-fit electrical connection to the electronics board has been disconnected, the differential pressure sensor can be removed and replaced without the need for further aids and instruments, in particular soldering tools. Since the inner housing and the oil store are omitted without being replaced, the differential pressure sensor can be replaced directly and in situ. The fact that the differential pressure sensor is clamped between the housing portions increases the pressure resistance of the differential pressure sensor.
According to another feature of the invention, the faces of the differential pressure sensor that touch the flange faces of the housing portions are respectively separated by a seal.
This improves the sealing action between the differential pressure sensor and the housing portions, in particular at high pressures.
According to another feature of the invention, the seal is formed by an O-ring. Straightforward and cost-effective sealing is thereby achieved.
According to another feature of the invention, the seal is formed by a metallic layer which is electrolytically applied to the surface of the side of the differential pressure sensor pointing toward each flange face of the housing portions.